This invention relates to the dry forming of webs.
Dry forming implies that the fibre material dispersed in air is caused to flow against a running forming wire. The fibres precipitate on the wire while the air passes therethrough. In commercially available plants for dry forming, the web is formed by using nets or screen plates, through which the fibres are to pass prior to their precipitation on the wire. The finer the net, the cleaner the web, but at the same time the fibre flow is reduced and an ever increasing amount of fibres are separated as reject and recycled for repeated defibration. The result is low capacity and degradation of the fibres. A further disadvantage is that the fibres easily can clog the holes in the net or screen and thereby cause non-uniform fibre distribution.